This application claims priority from Japanese Patent Application No. 2001-368622 which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a flat cable and a laminated cable harness.
2. Description of the Art
Electric appliances for a vehicle, such as an automobile, include safety appliances, auxiliary appliances and so on. In recent years, these electric appliances have been increasing in function and in variety. At the same time, electric wiring connected to such electric appliances has become more complicated and higher in density.
A wire harness used for the electric wiring within an automobile includes a lot of cables. In fact, the number of cables in a wire harness varies depending upon the models and the classes of automobiles, and the total number of cables sometimes reaches up to 500, even to 800. If the number of cables bound or tied together within the wire harness is increased, the wire harness becomes large in the diameter thereof, thereby increasing the volume occupied by that wire harness. Thus, at the same time, a tact time (cycle time) necessary for tying up the cables as a wire harness becomes long when manufacturing a vehicle, thereby increasing the manufacturing cost of the wire harness.
Under the situation described above, there is a tendency to use a flat cable or a laminated cable harness in place of the wire harness. The flat cable contains flat lead wires embedded in a tape-shaped insulating sheath. The laminated cable harness is prepared by laminating a plurality of flat cables. Thus, the flat cable and cable harness have flexibility.
However, since the lead wires of the flat cable have covered together with the insulating sheath, it is not easy to make connection between each of the lead wires and an electrical connection line at an arbitrary position of the flat cable, different from the case of the wire harness. In other word, a branch connection of the flat cable cannot be performed easily.
To describe more specifically, in the case of the laminated cable harness, it is actually impossible to make such branch connection between one flat cable and the other flat cable, when another flat cable lies between those flat cables under the state that such branch connection is required.
To enable such branch connection as described above, it is necessary to provide junction equipment, such as a joint connector or a joint box. However, using such equipment not only makes the electric wiring within a vehicle more complicated, but also increases the length needed for the flat cable or the laminated cable harness.
It is an object of the present invention to provide a flat cable and a laminated cable harness obtained by laminating the flat cables for achieving reduction of the use of junction equipment and miniaturization of the electric wiring described above, namely a flat cable and a laminated cable harness for connecting and/or branching off lead wires thereof as desired and with ease.
To achieve the object described above, according to the present invention, there is provided a flat cable comprising a flat strip, including a plurality of lead wires extended in parallel with each other along the strip, and an insulating sheath for covering around the lead wires; and a lap section formed on the middle of the strip as a branch joint, said branch joint allowing one of connections between the lead wires and between the lead wire and an electric connection line, wherein the lap section is formed by folding the strip so as to lie one of adjacent two portions of the strip upon the other portion and projects in a width direction of the strip while being parallel with a remaining portion of the strip.
Further, to achieve the object described above, according to the present invention, there is provided a laminated cable harness comprising a plurality of flat cables laminated with one on top of the other, each of the flat cables includes: a flat strip having a plurality of lead wires extended in parallel with each other along the strip, and an insulting sheath covering the lead wires; and a lap section as a branch joint, formed on the middle of the strip, the branch joint allowing one of connections between the lead wires and between the lead wire and an electric connection line, wherein the lap section is formed by folding the strip so as to lie one of adjacent two portions of the strip upon the other portion and projects in a width direction of the strip while being parallel with a remaining portion of the strip, and the lap sections of the flat cables are located in tandem along a longitudinal direction of the laminated cable harness; and connecting member for being adapted to complet the branch joint.